Article with lubricated surface and method

ABSTRACT

A method for preparing one or more lubricated surfaces of an article to reduce the break-out force and sliding frictional force. A lubricant is applied to one or more surfaces, and the lubricant-coated surface is treated by exposing the surface to an energy source, wherein the energy source is an ionizing gas plasma at about atmospheric pressure, gamma radiation, or electron beam radiation. One or more of the surfaces may be exposed to the ionizing gas plasma at about atmospheric pressure prior to application of the lubricant. Another aspect of the invention is articles produced using one or more methods of the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application that claims priorityfrom U.S. patent application Ser. No. 10/791,542 filed on Mar. 2, 2004,entitled “Article with Lubricated Surface and Method,” which hassubsequently issued as U.S. Pat. No. 7,431,989, which in turn claims thebenefit of Provisional Application No. 60/468,156 filed May 6, 2003,entitled “Article Having Single-Layered Lubricant and Method Thereof.”

BACKGROUND

It is well known in the art that friction is the resistant force thatprevents two objects from sliding freely when in contact with oneanother. There are a number of different types of frictional forcesdepending upon the particular motion being observed. Static friction isthe force that holds back a stationary object up to the point where theobject begins to move. Kinetic friction is the resistive force betweentwo objects in motion that are in contact with one another. For any twoobjects in contact with one another, a value known as the coefficient offriction can be determined which is a relative measure of thesefrictional forces. Thus, there is a static coefficient of friction and akinetic coefficient of friction. Stated another way, the coefficient offriction relates to the amount of force necessary to initiate movementbetween two surfaces in contact with one another, or to maintain thissliding movement once initiated. Because of their chemical composition,physical properties, and surface roughness, various objects havedifferent coefficients of friction. Softer, more compliant materialssuch as rubber and elastomers tend to have higher coefficient offriction values (more resistance to sliding) than less compliantmaterials. The lower the coefficient of friction value, the lower theresistive force or the slicker the surfaces. For example, a block of iceon a polished steel surface would have a low coefficient of friction,while a brick on a wood surface would have a much higher coefficient offriction.

The difference between the static and kinetic coefficients of frictionis known as “stick-slip.” The stick-slip value is very important forsystems that undergo back-and-forth, stop-and-go, or very slow movement.In such systems, a force is typically applied to one of the two objectsthat are in contact. This force must be gradually increased until theobject begins to move. At the point of initial motion, referred to as“break-out,” the static friction has been overcome and kineticfrictional forces become dominant. If the static coefficient of frictionis much larger than the kinetic coefficient of friction, then there canbe a sudden and rapid movement of the object. This rapid movement may beundesirable. Additionally, for slow moving systems, the objects maystick again after the initial movement, followed by another suddenbreak-out. This repetitive cycle of sticking and break-out is referredto as “stiction.”

In order to minimize the friction between two surfaces, a lubricant canbe applied which reduces the force required to initiate and maintainsliding movement. However, when two lubricated surfaces remain incontact for prolonged periods of time, the lubricant has a tendency tomigrate out from the area of contact due to the squeezing force betweenthe two surfaces. This effect tends to increase as the squeezing forceincreases. As more of the lubricant migrates from between the twosurfaces, the force required to initiate movement between the surfacescan revert to that of the non-lubricated surfaces, and stiction canoccur. This phenomenon can also occur in slow moving systems. Because ofthe slow speed, the time interval is sufficient to cause the lubricantto migrate away from the area of contact. Once the object moves past thelubricant-depleted area, the object comes into contact with alubricant-rich area. The frictional force is less in the lubricant-richarea and sudden, rapid movement of the object can occur.

Attempts have been made to reduce the migration of lubricant frombetween surfaces in contact with one another. In particular, methodsexist using an energy source to treat a lubricant applied to one or moreof the surfaces such that the migration is reduced.

Information relevant to attempts to address the above problems using agas plasma as the energy source for several specific embodiments can befound in the following U.S. patents: U.S. Pat. No. 4,536,179; No.4,767,414; No. 4,822,632; No. 4,842,889; No. 4,844,986; No. 4,876,113;No. 4,960,609; No. 5,338,312; and No. 5,591,481. However, each one ofthese references suffers from the disadvantage of treating the lubricantlayer with an ionizing gas plasma generated under vacuum, rendering themethods impractical for large-scale production operations.

A need exists, therefore, for a method to produce a lubricated surfacein which the migration of lubricant from the area of contact between twosurfaces is reduced such that the break-out force and sliding frictionalforce are minimized, such method not being conducted under vacuum. Aneed also exists for articles produced by such a method.

SUMMARY

The present invention is directed to a method and articles that satisfythese needs. One aspect of the invention comprises a method to reducethe migration of lubricant between surfaces in sliding frictionalcontact with one another. A lubricant is applied to one or more of thesurfaces, then the lubricant is exposed to an energy source at aboutatmospheric pressure to treat the lubricant. Another aspect of theinvention comprises using an ionizing gas plasma at about atmosphericpressure as the energy source. Yet another aspect of the inventioncomprises using ionizing radiation as the energy source, such as gammaradiation produced by, for example, cobalt-60 and cesium-137 sources.Still another aspect of the invention comprises using electron beamradiation as the energy source. Yet another aspect of the inventioncomprises additionally exposing the surface to the ionizing gas plasmaprior to application of the lubricant. The reduced migration of thelubricant minimizes the stiction phenomenon common to surfaces insliding contact with one another, thereby reducing the break-out forceand sliding frictional force.

Still another aspect of the invention comprises articles produced inaccordance with at least one of the methods of the invention to reducethe migration of lubricant from two or more surfaces in contact with oneanother to minimize stiction. Yet another aspect of the inventioncomprises articles produced in accordance with one or more of themethods of the invention to minimize the sliding frictional force of asurface of the article.

Definitions

In the description that follows, a number of terms are used. In order toprovide a clear and consistent understanding of the specification andappended claims, including the scope to be given such terms, thefollowing definitions are provided:

About Atmospheric Pressure. An embodiment of the invention involves thegeneration of an ionizing gas plasma. While gas plasmas can be producedunder various levels of vacuum, the invention uses a plasma generated atessentially atmospheric pressure. While no conditions of vacuum orabove-atmospheric pressure are deliberately produced by carrying out themethod of the invention, the characteristics of the gas flow may createa deviation from atmospheric pressure. For example, when using a methodof the invention to treat the inside of a cylindrical object, the gasflowing into the cylinder may result in a higher pressure within thecylinder than outside the cylinder.

Break-Out. An embodiment of the invention involves surfaces in slidingcontact with one another. When the surfaces are in contact but at rest,a force must be applied to one of the surfaces to initiate movement.This applied force must be increased until the frictional forcesopposing movement are overcome. The point at which the applied forcejust surpasses the frictional force and movement is initiated is knownas break-out.

Chatter. Repetitive stick-slip movement associated with the movement ofsurfaces in contact with one another is known as chatter. When alubricant is present between the surfaces, chatter can occur when thelubricant is squeezed out from between the surfaces, resulting in anincrease in the coefficient of friction. A larger force must then beapplied to the surfaces in order to initiate movement, which can cause asudden, exaggerated movement. Chatter occurs when this cycle isrepetitive.

Coefficient of Friction. The coefficient of friction relates to theamount of force necessary to initiate movement between two surfaces incontact with one another, or to maintain this sliding movement onceinitiated. Numerically, the term is defined as the ratio of theresistive force of friction divided by the normal or perpendicular forcepushing the objects together.

Electron Beam Radiation. Electron beam radiation is a form of ionizingradiation produced by first generating electrons by means of an electrongun assembly, accelerating the electrons, and focusing the electronsinto a beam. The beam may be either pulsed or continuous.

Friction. Friction is a resistive force that prevents two objects fromsliding freely against each other.

Functionalized Perfluoropolyether. A perfluoropolyether where one ormore of the fluorine atoms have been replaced by reactive functionalgroups.

Gamma Radiation. Gamma radiation is a type of electromagnetic waveform,often emitted at the same time the unstable nucleus of certain atomsemits either an alpha or beta particle when the nucleus decays. Gammaradiation, being an electromagnetic waveform, is similar to visiblelight and x-rays but of a higher energy level which allows it topenetrate deep into materials.

Gas Plasma. When sufficient energy is imparted to a gas, electrons canbe stripped from the atoms of the gas, creating ions. Plasma containsfree-moving electrons and ions, as well as a spectrum of electrons andphotons.

Lubricant-solvent solution (coating solution). The lubricant may bediluted with an appropriate solvent prior to applying the lubricant ontothe surface. The resulting mixture of lubricant and solvent is known asa lubricant-solvent solution.

Ionizing. Ionizing means that enough energy is present to break chemicalbonds.

Parking. Syringes used in medical applications are often pre-filledprior to use and stored. The amount of time between filling the syringeand discharging the syringe is known as parking time. In general,parking increases the break-out force.

Perfluoropolyether. A perfluoropolyether is a compound with the generalchemical structure of:

Stiction. The overall phenomenon of stick-slip is known as stiction.

Stick-Slip. The difference between static and kinetic coefficients offriction is known as stick-slip. In systems where a lubricant ispresent, high mating forces can squeeze the lubricant out from betweenthe surfaces in contact with one another. An increased force is thenrequired to initiate sliding movement of the surfaces. This movement mayoccur suddenly, caused by the surfaces coming into contact with alubricant-rich area. If the lubricant is again forced out from betweenthe surfaces, they can begin to bind. The sliding motion can stop untilthe force is increased enough to once again initiate movement. Thisalternating sticking and slipping is called stick-slip.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was coated with a specific lubricant and treated for varioustimes by an ionizing gas plasma at about atmospheric pressure.

FIG. 2 shows in greater detail a portion of the experimentalmeasurements from FIG. 1.

FIG. 3 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was coated with a specific lubricant and treated for varioustimes by an ionizing gas plasma at about atmospheric pressure.

FIG. 4 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was coated with a specific lubricant and treated for 30 secondsby an ionizing gas plasma at about atmospheric pressure.

FIG. 5 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was coated with a specific lubricant and treated for varioustimes by an ionizing gas plasma at about atmospheric pressure, thenparked for one week.

FIG. 6 is a plot of experimental measurements of the break-out force andsliding force applied to a syringe plunger as a function of treatmenttime with an ionizing gas plasma at about atmospheric pressure.

FIG. 7 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was coated with a specific lubricant and treated for varioustimes by an ionizing gas plasma at about atmospheric pressure.

FIG. 8 is a plot of experimental measurements of the force applied to asyringe needle as a function of insertion time, where the needle wascoated with various lubricants and treated for a specific time by anionizing gas plasma at about atmospheric pressure. The force wasmeasured as the needle was inserted into a pharmaceutical closurestopper.

FIG. 9 is a plot of experimental measurements of the force applied to asyringe needle as a function of the number of penetrations into apharmaceutical closure stopper, where the needle was coated with variouslubricants and treated for a specific time by an ionizing gas plasma atabout atmospheric pressure.

FIG. 10 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was made of glass and was coated with various lubricants andtreated for a specific time by an ionizing gas plasma at aboutatmospheric pressure.

FIG. 11 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was coated with a specific lubricant and treated for a specifictime by an ionizing gas plasma at about atmospheric pressure. Theinfusing medium was a high viscosity liquid.

FIG. 12 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was coated with a specific lubricant and treated for a specifictime by ionizing gamma radiation.

FIG. 13 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was coated with a specific lubricant and treated for a specifictime by ionizing gamma radiation.

FIG. 14 is a plot of experimental measurements of the force applied to asyringe plunger as a function of infusion time, where the barrel of thesyringe was treated for a specified time by ionizing gas plasma at aboutatmospheric pressure, coated with a specific lubricant, and treated fora specific time by an ionizing gas plasma at about atmospheric pressure.

DESCRIPTION

It is understood that the embodiments described herein are intended toserve as illustrative examples of certain embodiments of the presentinvention. Other arrangements, variations, and modifications of thedescribed embodiments of the invention may be made by those skilled inthe art. No unnecessary limitations are to be understood from thisdisclosure, and any such arrangements, variations, and modifications maybe made without departing from the spirit of the invention and scope ofthe appended claims. Stated ranges include the end points of the rangeand all intermediate points within the end points.

A method according to the present invention for reducing the migrationof lubricant from between surfaces in contact with one another comprisesapplying a lubricant to one or more of the surfaces, then treating thelubricant-coated surface by exposing it to an energy source. Anothermethod according to the present invention comprises exposing the surfaceto an energy source, specifically an ionizing gas plasma at aboutatmospheric pressure, prior to the application of the lubricant. It istheorized that exposing the surface to the ionizing gas plasma at aboutatmospheric pressure prior to applying the lubricant creates activesites on the surface that facilitate the reduced migration of thelubricant. As a result of these methods, the lubricant resists migratingfrom between the surfaces in contact with one another, thereby reducingthe break-out force and sliding frictional force. Optionally, any of themethods of the present invention can be applied to only one surface ofan object.

The lubricant can be applied to the surface of the object by any of thenumerous methods know in the art. By way of example, suitableapplication methods include spraying, atomizing, spin casting, painting,dipping, wiping, tumbling, and ultrasonics. The method used to apply thelubricant is not essential to the performance of the invention.

The lubricant may be a fluorochemical compound or a polysiloxane-basedcompound. In one embodiment of the present invention, the fluorochemicalcompound is a perfluoropolyether (PFPE). Representative examples ofcommercially available PFPE include, for example, Fomblin M® and FomblinY® families of lubricants from Solvay Solexis, Krytox® from E.I. du Pontde Nemours and Company, and Demnum™ from Daikin Industries, Limited.Table 1 presents the chemical structures of these compounds, and Table 2presents the molecular weights and viscosities. In another embodiment ofthe invention, the lubricant is a functionalized PFPE. Representativeexamples of commercially available functionalized PFPE include, forexample, Fomblin ZDOL®, Fomblin ZDOL TXS®, Fomblin ZDIAC®, FluorolinkA10®, Fluorolink C®, Fluorolink D®, Fluorolink E®, Fluorolink E10®,Fluorolink E10®, Fluorolink L®, Fluorolink L10®, Fluorolink S10®,Fluorolink T®, and Fluorolink T10®, from Solvay Solexis as shown inTable 3. In yet another embodiment of the invention, the functionalizedPFPE may be an emulsion. Representative example of commerciallyavailable functionalized PFPE emulsions are, for example, FomblinFE-20C® and Fomblin FE-20AG® from Solvay Solexis. In yet anotherembodiment of the invention, the fluorochemical compound is achlorotrifluoroethylene. A representative example of commerciallyavailable chlorotrifluoroethylene is, for example, Daifloil™ from DaikinIndustries, Limited (see Table 2). In still another embodiment of theinvention, the polysiloxane-based compound is a silicone oil with adimethlypolysiloxane chemical formulation of the following generalchemical structure:

The number of repeating siloxane units (n) in the polymer chain willdetermine the molecular weight and viscosity of the silicone oil. As thenumber of siloxane units increases, the polymer becomes longer and boththe molecular weight and viscosity increases. Generally, the usableviscosity range of silicone oils is about 5-100,000 centistokes.

The lubricant can be applied in a diluted or non-diluted form, andcombinations of diluted or non-diluted lubricants can be used. Thelubricant can also be applied as a water dispersion or as an emulsion.Any suitable solvent can be used as the diluent that is compatible withthe lubricant or combination of lubricants used. By way of example, aperfluorinated solvent can be used with a perfluoropolyether lubricant.The resulting mixture of one or more lubricants and one or more solventsis known as a lubricant-solvent solution. The lubricant may be dilutedin order to facilitate the application of a thin film of the lubricantonto the surface of the object. The amount of dilution, or weightpercent of lubricant in the lubricant-solvent solution, is not essentialto the performance of the invention. The weight percent of lubricant inthe solvent, when a solvent is used, may be greater than or equal toabout 0.1 percent, such as, for example, 1, 10, 20, 30, 40 and 50. Theweight percent of the lubricant in the solvent may also be less than orequal to about 95 percent, such as, for example, 90, 80, 70, and 60. Thediluent solvent is evaporated prior to exposure to the energy source.

For commercialization purposes when a lubricant-solvent solution isused, it may be advantageous to heat the surface after applying thelubricant-solvent solution but before exposing the coated surface to theenergy source. The purpose of this step is to facilitate the evaporationof the solvent. When articles are mass-produced according to the methodsof the present invention, it may be necessary to minimize the timebetween application of the lubricant-solvent mixture and exposing thecoated surface to the energy source. Therefore, the heating step willcause the solvent to evaporate quicker than at ambient conditions. Whilethe solvent can be evaporated at ambient conditions, elevatedtemperatures up to about 150° C. can be used. Depending on the surfacematerial, the heating step generally can be carried out at anyconvenient temperature between ambient and about 150° C., generally inthe range of about 80° C. to about 130° C. The amount of time that thecoated surface is heated depends on a number of factors including, byway of example, the viscosity and vapor pressure of the solvent, thethickness of the lubricant-solvent solution layer applied to thesurface, and the geometric configuration of the surface. The amount oftime the coated surface is heated may be greater than or equal to about0.5 minute, such as, for example, 1, 5, 10, and 20 minutes. The amountof time the coated surface is heated may also be less than about 60minutes, such as, for example, about 50, 40, and 30 minutes.

In addition to being diluted prior to application, the lubricant mayalso include additives. The additives include, for example, free radicalinitiators such as peroxides and azo nitriles; viscosity modifiers orthickening agents such as fluoroelastomers, silica, and Teflon®particles; surfactants or wetting agents; anticorrosion or rustinhibiting agents, antioxidants, antacids, antiwear agents, bufferingagents, and dyes.

In one embodiment of the invention, the energy source is an ionizing gasplasma. The gas may be a noble gas including, for example, helium, neon,argon, and krypton. Alternatively, the gas may be an oxidiative gasincluding, for example, air, oxygen, carbon dioxide, carbon monoxide,and water vapor. In yet another alternative, the gas may be anon-oxidative gas including, for example, nitrogen and hydrogen.Mixtures of any of these gases may also be used.

The exact parameters under which the ionizing gas plasma are generatedare not critical to the methods of the invention. These parameters areselected based on factors including, for example, the gas in which theplasma is to be generated, the electrode geometry, radio frequency ofthe power source, and the dimensions of the surface to be treated. Thetreatment time may range from about 0.001 second to about 10 minutes, inaddition ranging from about 0.001 second to about 5 minutes, and furtherin addition ranging from about 0.01 second to about 1 minute. The radiofrequency may range from about 0.5 kilohertz to about 15,000 kilohertz,in addition ranging from about 1 kilohertz to about 100 kilohertz, andfurther in addition ranging from about 3 kilohertz to about 10kilohertz. The power setting may be less than or equal to, for example,about 1 kilowatt.

In another embodiment of the invention the lubricant-coated surface isexposed to ionizing radiation which provides the energy necessary totreat the lubricant. The ionizing radiation source can be gammaradiation or electron-beam radiation. Typically, commercial gammairradiation processing systems use cobalt-60 as the gamma radiationsource, although cesium-137 or other gamma radiation source may also beused. Commercial electron-beam radiation systems generate electrons froman electricity source using an electron gun assembly, accelerate theelectrons, then focus the electrons into a beam. This beam of electronsis then directed at the material to be treated. The lubricant-coatedsurface may be exposed to an ionizing radiation dosage ranging fromabout 0.1 megarad to about 20 megarads, in addition ranging from about0.5 megarad to about 15 megarads, and further in addition ranging fromabout 1 megarad to about 10 megarads.

TABLE 1 CHEMICAL STRUCTURE OF EXAMPLE PERFLUOROPOLYETHER (PFPE)COMPOUNDS PFPE Compound Chemical Structure Fomblin M ® and Fomblin Z ®CF₃[(—O—CF₂—CF₂)p—(O—CF₂)q]—O—CF₃ (Solvay Solexis) (p + q = 40 to 180and p/q = 0.5 to 2) Fomblin Y ® (Solvay Solexis)

Krytox ® (E.I. du Pont de Nemours and Company)

Demnum ™ F—(CF₂—CF₂—CF₂—O)n—CF₂—CF₃ (Daikin Industries, Limited) (n = 5to 200)

TABLE 2 MOLECULAR WEIGHT AND VISCOSITY OF EXAMPLE PERFLUOROPOLYETHER(PFPE) COMPOUNDS Molecular Weight (atomic mass Viscosity PFPE Compoundunits) (centistokes, 20° C.) Fomblin M ® and Fomblin Z ® 2,000-20,00010-2,000 (Solvay Solexis) Fomblin Y ® 1,000-10,000 10-2,500 (SolvaySolexis) Krytox ®   500-12,000  7-2,000 (E.I. du Pont de Nemours andCompany) Demnum ™ 1,000-20,000 10-2,000 (Daikin Industries, Limited)Daifloil ™  500-1,100  5-1,500^(a) (Daikin Industries, Limited)^(a)Viscosity at 25° C.

TABLE 3 FUNCTIONAL GROUPS, MOLECULAR WEIGHT, AND VISCOSITY OFFUNCTIONALIZED PERFLUOROPOLYETHER (PFPE) COMPOUNDS Number of FunctionalViscosity Functionalized Groups per Molecular Weight (centistokes, PFPECompound Functional Group Molecule (atomic mass units) 20° C.) FomblinZDOL ® Alcohol 1-2 1,000-4,000  50-150 Fluorolink D ® —CH₂(OH) (SolvaySolexis) Fomblin ZDOL Alcohol 1-2 1,000-2,500  80-150 TXS ® FluorolinkE ® —CH₂(OCH₂CH₂)nOH Fluorolink E10 ® (Solvay Solexis) Fluorolink T ®Alcohol 2-4 1,000-3,000 2,000-3,000 Fluorolink T10 ® —CH₂OCH₂CH(OH)CH₂OH(Solvay Solexis) Fomblin ZDIAC ® Alkly Amide 1-2 1,800 Wax FluorolinkC ® —CONHC₁₈H₃₇ (Solvay Solexis) Fluorolink L ® Ester 1-2 1,000-2,00010-25 Fluorolink L10 ® —COOR (Solvay Solexis) Fluorolink S10 ® Silane1-2 1,750-1,950   170 (Solvay Solexis) Fluorolink F10 ® Phosphate 1-22,400-3,100 18,000 (Solvay Solexis)

EXAMPLE 1

A coating solution was made by preparing a 90:10 mixture by weight ofFomblin Perfluorosolve™ PFS-1 (Solvay Solexis, Inc.) and Fomblin M100®lubricant. Non-lubricated injection molded 10 cc polypropylene syringebarrels were filled with the coating solution and allowed to drain. Thesyringe barrels were allowed to air dry to evaporate the solvent,leaving a thin layer of the lubricant on the surface. After drying, theinner cavities of the syringe barrels were exposed to an argon ionizingplasma at about atmospheric pressure for 10, 20, and 40 seconds at anargon gas flow rate of 5 cubic feet per minute (cfm). The syringebarrels were then assembled with non-lubricated plungers and mounted ona motorized syringe pump. The syringe pump was fitted with a digitalforce gauge to record the compressive forces. The force required to pushthe plunger down the barrel at an infusion rate of 1 cc/min is shown inFIGS. 1 and 2. FIG. 1 clearly shows that both the break-out force andthe stick-slip chatter were dramatically reduced for all of the syringebarrels that were lubricated and plasma treated. The syringe barrel thatwas lubricated but not plasma treated required a force of about 14 to 18pounds to achieve break-out and exhibited repeated chatter. All of thesyringe barrels that were lubricated and plasma treated required a forceof about 3 to 4.5 pounds to achieve break-out and exhibited nodiscernable chatter. FIG. 2 is an expanded plot showing the effect ofthe different plasma exposure times.

EXAMPLE 2

Example 1 was repeated except the Fomblin M100® lubricated syringebarrel was exposed to a plasma at about atmospheric pressure using a50/50 mixture of argon and helium. The gas flow rate was 2.5 cfm argonand 2.5 cfm helium, and the exposure time was 40 seconds. The effect ofthis argon/helium mixture is also presented in FIGS. 1 and 2.

EXAMPLE 3

A coating solution was made by preparing a 90:10 mixture by weight ofFomblin Perfluorosolve™ PFS-1 and Fomblin M30® lubricant. Non-lubricatedinjection molded 10 cc polypropylene syringe barrels were filled withthe coating solution and allowed to drain. The syringe barrels wereallowed to air dry to evaporate the solvent, leaving a thin layer oflubricant on the surface. After drying, the inner cavity of the syringebarrels were exposed to an argon ionizing plasma at about atmosphericpressure for 10, 20, and 40 seconds at an argon gas flow rate of 5 cfm.The syringe barrels were assembled with non-lubricated plungers andmounted on a motorized syringe pump. The syringe pump was fitted with adigital force gauge to record the compressive forces. The force requiredto push the plunger down the barrel at an infusion rate of 3 cc/min isshown in FIG. 3. FIG. 3 clearly shows that both the break-out force andthe stick-slip chatter were dramatically reduced for all of the syringebarrels that were lubricated and plasma treated. The syringe barrel thatwas lubricated but not plasma treated required a force of about 17 to 19pounds to achieve break-out and exhibited repeated chatter. All of thesyringe barrels that were lubricated and plasma treated required a forceof about 3 pounds to achieve break-out and exhibited no discerniblechatter.

EXAMPLE 4

A coating solution was made by preparing a 95:5 mixture by weight ofFomblin Perfluorosolve™ PFS-1 and Fomblin YR® lubricant. Non-lubricatedinjection molded 10 cc polypropylene syringe barrels were filled withthe coating solution and allowed to drain. The syringe barrels wereallowed to air dry to evaporate the solvent, leaving a thin layer of thelubricant on the surface. After drying, the inner cavities of thesyringe barrels were exposed to an argon ionizing plasma at aboutatmospheric pressure for 30 seconds at an argon gas flow rate of 5 cfm.The syringe barrels were assembled with non-lubricated plungers andmounted on a motorized syringe pump. The syringe pump was fitted with adigital force gauge to record the compressive forces. The force requiredto push the plunger down the barrel at an infusion rate of 1 cc/min isshown in FIG. 4. This figure clearly shows that both the break-out forceand the stick-slip chatter were dramatically reduced for all of thesyringe barrels that were lubricated and plasma treated. The syringebarrel that was lubricated but not plasma treated required a force ofabout 6 to 9 pounds to achieve break-out and exhibited repeated chatter.The syringe barrel that was lubricated and plasma treated required aforce of about 4 pounds to achieve break-out and exhibited nodiscernible chatter.

EXAMPLE 5

Example 1 was repeated with plasma exposure times of 3, 5, 10, 20, and40 seconds. The syringe barrels were lubricated, plasma treated,assembled with plungers, and stored at room temperature for 7 days withthe plungers parked in the barrels in the same position for the entireduration before they were tested. The 7-day parking time allowed theapplied lubricant coating to achieve equilibrium with respect to anymigration on the surface due to compressive forces between the plungerand the barrel. FIG. 5 shows that the break-out force was about 1.5 to 3pounds and that there was no discernible stick-slip chatter. Theseresults are consistent with the previous examples where there wasessentially no parking time between plasma treatment and testing. Thedata strongly indicate that the lubricant was immobilized by the plasmatreatment and did not migrate out from the plunger-barrel interface,even after extended parking times. FIG. 6 plots the break-out force andsliding force versus the plasma treatment time. The data show that thebreak-out force was influenced by the exposure time to the ionizingplasma, reaching a minimum of about 1.5 pounds at 10 seconds treatmenttime and then rising to about 3 pounds with increasing treatment time.The sliding force also showed a slight trend of increasing force withincreasing treatment time, although generally remaining at about 1pound.

EXAMPLE 6

Commercially available syringe barrels pre-lubricated with silicone oilwere exposed to an argon ionizing plasma at about atmospheric pressureas described in Example 1. The argon gas flow rate was 5 cfm and theexposure times were 20 and 40 seconds. These syringe barrels were testedidentically as described in the previous examples at an infusion rate of3 cc/min. The resulting data are shown in FIG. 7. These data clearlyshow that stick-slip chatter is inherent in some commercially availablesyringes pre-lubricated with silicone oil and that ionizing plasmatreatment at about atmospheric pressure dramatically reduced break-outforces and eliminated stick-slip chatter. The syringe barrel that waspre-lubricated but not plasma treated required a force of about 4.5pounds to achieve break-out and exhibited repeated chatter. The syringebarrels that were pre-lubricated and plasma treated required a force ofabout 1.5 to 2 pounds to achieve break-out and exhibited no discerniblechatter.

EXAMPLE 7

Coating solutions were made by preparing a 99:1 and 98:2 mixture byweight of Fomblin Perfluorosolve™ PFS-1 and Fomblin M100® lubricant. Thecoating solutions were applied to clean 25-gauge syringe needles. Thesyringe needles were allowed to air dry to evaporate the solvent. Afterdrying, the needles were exposed to an argon ionizing plasma at aboutatmospheric pressure for 15 seconds. The force required for penetrationof the needles into pharmaceutical closure stoppers was measured using adigital force gauge. FIG. 8 illustrates the forces in kilograms forsyringe needles prepared according to the following three scenarios: 1)no lubrication and no plasma treatment, 2) lubricated but no plasmatreatment, and 3) lubricated and plasma treated. The penetration forcewas greatly reduced by the plasma treatment. The needle that was neitherlubricated nor plasma treated required a force of about 0.7 kilograms.The lubricated but not plasma treated needle required a force of about0.5 kilograms and exhibited chatter. The lubricated and plasma treatedneedles required a force of about 0.2 to 0.25 kilograms and exhibited nodiscernible chatter.

EXAMPLE 8

A coating mixture was made by preparing a 60:40 mixture by weight ofFomblin M100® and Fomblin ZDOL® lubricants. This mixture was thendiluted 95:5 by weight with Fomblin Perfluorosolve™ PFS-1. The coatingsolution was applied to clean 21-gauge syringe needles. The syringeneedles were then allowed to air dry to evaporate the solvent, leaving athin layer of the lubricants on the surface. The syringe needles werethen exposed to a helium ionizing plasma at about atmospheric pressurefor 5 seconds. The syringe needles were then tested for penetrationforce into pharmaceutical closure stoppers for a total of 5penetrations. FIG. 9 illustrates the peak forces in pounds for thesesamples in comparison to silicone-coated syringe needles that were notplasma treated and uncoated syringe needles. The penetration force wasgreatly reduced by the plasma treatment. The non-lubricated and notplasma treated needle required a force of about 2.1 pounds for the firstpenetration, falling to about 1.6 pounds after 5 penetrations. Theneedle coated with silicone but not plasma treated required a force ofabout 0.7 pounds for the first penetration, increasing to about 1.1pounds after 5 penetrations. The needle that was lubricated and plasmatreated required a force of about 0.6 pounds for the first penetration,increasing to about 0.8 pounds after 5 penetrations.

EXAMPLE 9

Glass syringes (size 10 cc), which are typically used in pre-filledsyringes, were tested in this example. A coating solution was made bypreparing a 25:25:50 mixture by weight of Fomblin ZDOL®, Fomblin M30®,and Fomblin M60®, respectively. The resulting coating solution contained2% by weight of PFPE solids. After application of the coating solutionto the inside of the syringe barrels, they were allowed to air dry toevaporate the solvent, leaving a thin layer of the lubricants on thesurface. The syringe barrels were then exposed to a helium ionizingplasma at atmospheric pressure for 3 seconds. The syringes barrels werethen assembled with butyl rubber plungers and 23 gauge cannula andparked for 3 days. The force required to infuse deionized water was thenmeasured. FIG. 10 presents these data, as well as the force measurementsfor commercially available syringes pre-lubricated with silicone oilthat were not plasma treated. The plasma treated syringes exhibitreduced force as compared to the syringes that were not plasma treated.The syringe that was lubricated with silicone oil but not plasma treatedrequired a force of about 1.6 pounds to achieve break-out, then achieveda relatively constant sliding force of about 1.2 pounds. The lubricatedand plasma treated syringe required about 1.3 pounds to achievebreak-out, then achieved a relatively constant sliding force of about 1pound. Neither syringe exhibited any discernible chatter,

EXAMPLE 10

Syringes (size 60 cc) used for power injection of contrast media wereused in this example. The syringe barrels were made of PET polymer andthe rubber plunger was butyl rubber. The contrast media used forinfusion was Visipaque 320® manufactured by Amersham Health. Visipaque320® is a viscous liquid with a viscosity of approximately 70centipoise. Commercially available syringes pre-lubricated with siliconeoil typically display forces in excess of 100 pounds when tested attypical infusion rates of 20-30 cc/sec. In this example, a coatingsolution was made by preparing a 90:10 mixture by weight of FomblinPerfluorosolve™ PFS-1 and Fomblin M100® lubricant. The syringe barrelswere filled with the coating solution and allowed to drain. The syringebarrels were allowed to air dry to evaporate the solvent, leaving a thinlayer of the lubricant on the surface. After drying, the syringe barrelswere exposed to a 50:50 argon and helium ionizing plasma at aboutatmospheric pressure for 20 seconds. The samples were then tested forinfusion force of the contrast media. FIG. 11 shows the infusion forcesat various infusion rates up to 35 cc/sec and clearly shows the lowerforces observed in the syringe barrels that were lubricated and plasmatreated as compared to the syringe barrels pre-lubricated with siliconeoil, but not plasma treated. The syringe barrels that were not plasmatreated required a force of about 90 to 170 pounds to achieve break-outdepending on the infusion rate. The syringe barrels that were lubricatedand plasma treated required only about 10 to 40 pounds to achievebreak-out over the same infusion rate range.

EXAMPLE 11

A coating solution was made by preparing a 90:10 mixture by weight ofFomblin Perfluorosolve™ PFS-1 and Fomblin M100® lubricant.Non-lubricated injection molded 10 cc polypropylene syringe barrels werefilled with the coating solution and allowed to drain. The syringebarrels were allowed to air dry to evaporate the solvent, leaving a thinlayer of the lubricant on the surface. The syringe barrels were thenexposed to ionizing radiation that was generated using a cobalt-60source. The total dose of exposure was about 3 megarads. The syringebarrels were tested for infusion forces before and after exposure to theionizing radiation. FIG. 12 presents the resulting data for the syringebarrels exposed to the ionizing radiation and those not exposed to theionizing radiation at an infusion rate of 1 cc/min, and FIG. 13 presentsthe resulting data for a similar test at an infusion rate of 10 cc/min.Both FIG. 12 and FIG. 13 demonstrate that the ionizing radiation energysource dramatically reduced break-out forces and eliminated stick-slipchatter. At an infusion rate of 1 cc/min, the syringe barrel that waslubricated but not exposed to the ionizing radiation required a force ofabout 20 to 22 pounds to achieve break-out and exhibited repeatedchatter. The syringe barrel that was lubricated and exposed to theionizing radiation required a force of about 2 pounds to achievebreakout and exhibited no discernible chatter. At an infusion rate of 10cc/min, the syringe barrel that was lubricated but not exposed to theionizing radiation required a force of about 7 to 10 pounds to achievebreak-out and exhibited repeated chatter. The syringe barrel that waslubricated and exposed to the ionizing radiation required a force ofabout 3 pounds to achieve breakout and exhibited no discernible chatter.

EXAMPLE 12

Glass syringes (size 1 cc), which are typically used in pre-filledsyringes, were tested in this example. A coating solution was made bypreparing a 80:20 mixture by weight of Fomblin ZDOL® and Fomblin M03®,respectively. The resulting coating solution contained 5% by weight ofthe PFPE solids. The syringe barrel was first cleaned with deionizedwater and allowed to dry. The syringe barrels were then exposed to a50:50 argon and helium ionizing gas plasma at about atmospheric pressurefor 5 seconds. After exposure to the ionizing gas plasma, the coatingsolution was applied to the inside surface of the syringe barrel. Thecoated syringe barrel was then heated to accelerate the evaporation ofthe solvent, leaving a thin layer of the lubricant on the surface. Thecoated syringe barrels were then exposed to a helium ionizing gas plasmaat about atmospheric pressure for 5 seconds. The syringes were thenassembled with butyl rubber stoppers and 25 gauge needles. The forcerequired to infuse deionized water at 1 cc/min was then measured for thetreated syringe. FIG. 14 presents these data, as well as the forcemeasurements for commercially available 1 cc glass syringespre-lubricated with silicone oil but not plasma treated. The plasmatreated syringe exhibited reduced force as compared to the syringe thatwas not plasma treated. The syringe that was lubricated with siliconeoil but not plasma treated required a force of about 0.6 pounds toachieve break-out, then achieved a relatively constant sliding force ofabout 0.4 pounds. The plasma treated and lubricated syringe required aforce of about 0.25 pounds to achieve break-out, then achieved arelatively constant sliding force of about 0.2 pounds. Neither syringeexhibited any discernible chatter.

1. A method for preparing a lubricated surface of an article to reducethe break-out force and sliding frictional force, comprising: (a)providing one or more surfaces; (b) applying a lubricant to at least oneof the surfaces to form a coated surface, the lubricant including afluorochemical compound selected from the group consisting of aperfluoropolyether, a functionalized perfluoropolyether, apolychlorotrifluoroethylene and mixtures thereof; and (c) exposing thecoated surface to an ionizing gas plasma at about atmospheric pressure.2. The method of claim 1 further comprising mixing the lubricant with asolvent to form a lubricant-solvent solution prior to applying thelubricant to the surface.
 3. The method of claim 2 further comprisingheating the coated surface, the heating step occurring after applyingthe lubricant-solvent solution to the surface and prior to exposing thecoated surface to the energy source.
 4. The method of claim 1 whereinapplying the lubricant to at least one of the surfaces to form thecoated surface comprises applying the lubricant to at least one of thesurfaces to form the coated surface, wherein the lubricant containsadditives selected from one or more groups comprising free radicalinitiators, viscosity modifiers, surfactants, wetting agents,anticorrosive agents, antioxidants, antiwear agents, buffering agents,dyes, and mixtures thereof.
 5. The method of claim 1 wherein exposingthe coated surface to the ionizing gas plasma further comprises formingthe ionizing gas plasma from a gas selected from one or more groupscomprising helium, neon, argon, krypton, air, oxygen, carbon dioxide,carbon monoxide, water vapor, nitrogen, hydrogen, and mixtures thereof.6. The method of claim 1 further comprising additionally exposing thesurface to the ionizing gas plasma prior to applying the lubricant. 7.The method of claim 1, wherein providing one or more surfaces comprisesproviding one or more surfaces constructed of polypropylene.
 8. Themethod of claim 1, wherein providing one or more surfaces comprisesproviding one or more surfaces constructed of glass.
 9. The method ofclaim 1, wherein providing one or more surfaces comprises providing asyringe barrel with an inner surface, the inner surface coated with aperfluoropolyether and exposed to the ionizing gas plasma at aboutatmospheric pressure after being coated with the perfluoropolyether. 10.The method of claim 9, wherein providing the syringe barrel with aninner surface comprises exposing the inner surface to the ionizing gasplasma prior to applying the perfluoropolyether.
 11. The method of claim10, wherein providing the syringe barrel comprises providing apolypropylene syringe barrel.
 12. The method of claim 10, whereinproviding the syringe barrel comprises providing a glass syringe barrel.13. A method for preparing a lubricated surface of an article to reducethe break-out force and sliding frictional force, comprising (a)providing one or more surfaces; (b) exposing at least one of thesurfaces to an ionizing gas plasma at about atmospheric pressure to forma plasma-treated surface; and (c) applying a lubricant to theplasma-treated surface to form a coated surface, the lubricant includinga fluorochemical compound selected from the group consisting of aperfluoropolyether, a functionalized perfluoropolyether, apolychlorotrifluoroethylene, and mixtures thereof.
 14. The method ofclaim 13 further comprising mixing the lubricant with a solvent to forma lubricant-solvent solution prior to applying the lubricant to theplasma-treated surface.
 15. The method of claim 14 further comprisingheating the coated surface, the heating step occurring after applyingthe lubricant-solvent solution to the plasma-treated surface.
 16. Themethod of claim 13 wherein applying the lubricant to the plasma-treatedsurface to form the coated surface comprises applying the lubricant tothe plasma-treated surface to form the coated surface, wherein thelubricant contains additives selected from one or more groups comprisingfree radical initiators, viscosity modifiers, surfactants, wettingagents, anticorrosive agents, antioxidants, antiwear agents, bufferingagents, dyes, and mixtures thereof.
 17. The method of claim 13 whereinexposing at least one of the surfaces to the ionizing gas plasma atabout atmospheric pressure comprises exposing at least one of thesurfaces to the ionizing gas plasma at about atmospheric pressure, theionizing gas plasma formed from a gas selected from one or more groupscomprising helium, neon, argon, krypton, air, oxygen, carbon dioxide,carbon monoxide, water vapor, nitrogen, hydrogen, and mixtures thereof.18. The method of claim 13, wherein providing one or more surfacescomprises providing an inner surface of a syringe barrel.
 19. The methodof claim 13, wherein applying the lubricant to the plasma-treatedsurface to form the coated surface comprises applying the lubricant toan inner surface of a syringe barrel to form the coated surface.
 20. Themethod of claim 19, wherein applying the lubricant to the inner surfaceof the syringe barrel to form the coated surface comprises applying thelubricant to the inner surface of a glass syringe barrel to form thecoated surface.